Earth and road roller

ABSTRACT

A roller for treating earth and pavement surfaces having a pair of drums skewed from the direction of roller travel, the skewed drums being skewed so as to have opposite and approximately equal effects on the steering of the roller.

nited States Patent 1191 Dermond EARTH AND ROAD ROLLER Hartley P. Dermond, 1385 Cumberland Rd, South Venice, Fla. 33595 Filed: Feb. 23, 1972 Appl. No.: 228,526

Inventor:

us. c1. 404/126 1m. c1., E016 19/23 Field 61 Search 404/103, 117, 122, 123, 404/125, 126, 127, 1223; 180/20; 172/513, 520

References Cited UNITED STATES PATENTS 7/1880 Patton 404/122 12/1899 Schaffer 172/584 Aug. 6, 1974 1,214,463 1/1917 HOiIZ 404/126 2,691,927 10/1954 Denton 404/125 x 2,985,079 5/1961 Clapper 404/123 x 3,303,762 2/1967 Jennings 404/1 17 FOREIGN PATENTS OR APPLICATIONS 1,110,677 7/1961 Germany 404/117 Primary Examiner-Roy D. Frazier Assistant Examiner-Thomas J. Holko 5 7 ABSTRACT A roller for treating earth and pavement surfaces having a pair of drums skewed from the direction of roller travel, the skewed drums being skewed so as to have opposite and approximately equal effects on the steering of the roller.

2 Claims, 6 Drawing Figures PATENIE AUB sum I I l I I I I PAIENIEMUB W 4 3,827,819

sum 20? 2 EARTH AND ROAD ROLLER FIELD OF THE INVENTION This invention relates to an earth surface treating machine and particularly to an improved surface roller.

BACKGROUND OF THE INVENTION There are many industrial situations in which it is necessary to develop a smooth and uniformly compacted earth or other material surface. One obvious situation is the development of the subsurface and the tinish surface of a plane landing strip or a road. Uniformity of compaction and surface smoothness are of particular importance to heavy duty roads. Failure to achieve uniform compaction tends to produce uneven surface wear with use. Furthermore, irregularities in the surfacing of a road (whether caused by uneven surface wear or by inadequate surface smoothing) provide sites for rapid surface deterioration with use.

Modern automobiles and even large trucks have improved suspension and shock absorbing devices which serve to provide a relatively smooth ride even over rough surfaces. Although a ride may appear smooth to a vehicle passenger, the wheels of the vehicle are set in vertical motion by surface irregularities. When a pneumatic rubber tire rolls over a surface irregularity which protrudes above the average road surface, the wheel momentarily leaves the surface and then lands with substantial downward force which is combined with a frictional force as the moving wheel engages the road surface. Such surface engagement tends to create a depression in the road surface. Similarly, when a moving wheel falls into even a small depression, there is an erosion of surface material as the wheel moves out of and past the depression. Although the greatest road damage is caused by large and often overloaded trucks and trailers, some erosion of the type above described can be attributed to even the smallest cars.

Since surface irregularities, both protrudances and depressions, cause surface degradation with use it is essential that a road surface be initially made as smooth as possible.

Historically, a road is built of a foundation layer comprised of relatively large stones which provide a bearing surface and drainage, an intermediate layer of smaller stones and binder and finally a surface layer comprised of by way of example of bituminous materials. As each layer is placed it is smoothed by a blade carrying machine, e.g., a wheeled road grader, and then compacted by a road roller.

Modern highways are often constructed initially of concrete which may exhibit a rough surface having a relatively regular pattern. Such pattern generally comprises ribs which run across the width of the highway. With use such a highway becomes rougher, however, a relatively regular pattern of roughness is retained. As a cure for such a surface condition it is common to refinish the surface with a relatively thin layer of asphalt which is rolled. Where conventional road rollers are utilized in such resurfacing the resulting surface has a modified pattern of the original rough surface condition.

Priorly known road rollers comprise two or more large weighted drums. At least one of the drums is driven to provide propelling power, and usually one drum is pivotally connected to the body of theroller and is adapted to be manually rotated to steer the'roller in a desired path. In prior known road rollers, the drums are connected to the roller body by axles and the axle of all drums, other than the one used to steer the roller, are rigidly maintained parallel to each other. In certain earth rollers the drum axles are permitted to move with respect to one and another to accommodate roller position to surface irregularities. However, even in such rollers which have an articulated mounting, the drums are advanced over the surface in a path which is perpendicular to the axles. Thus, in such prior art rollers the drums advance over the surface in a pure rolling motion except when the direction of the roller intentionally is changed.

SUMMARY OF THE INVENTION In accordance with my invention, a road roller comprises at least two surface treating drums which are mounted on the body of the roller by axles which are held in a common horizontal plane but which are skewed with respect to each other and to a line perpendicular to the direction of travel when the roller is viewed from above or below.

Advantageously, drums so mounted move across the treated surface with a combined rolling and translation motion. Such combined motion reduces the tendency of the roller to create surface irregularities and nonuniform material compaction.

Furthermore, where a roller having a skewed pair of drums is utilized in the resurfacing of a concrete highway having the above described pattern of roughness, no such pattern occurs in the finished surface since the skewed drums tend to bridge across the high areas in the pattern.

The drums which are mounted on such skew positioned axles are mounted on the front or the rear of the roller. For the purpose of simplification of discussion herein, drums mounted on axles so skewed will be referred to herein as the skewed drums. The skewed drums may be of equal or unequal width. A drum which is mounted skewed relative to the direction of roller travel tends to cause the roller to favor a direction of travel in the direction perpendicular to the skewed axle. Accordingly, the axles of the drums of a skewed pair are mounted on the roller so as to create opposite and approximately equal tendencies. If the drums of a skewed pair are of equal width the individual drums are generally skewed equally and in opposite direction relative to the vertical plane which is perpendicular to the direction of roller motion. If the drums of a skewed pair are of unequal width the respective angles of the drum axles relative to the direction of roller motion are adjusted through experimentation to cause the two drums to have opposite and approximately equal effects in the DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENT FIG. 1 is a general top view of a roller which illustrates the principles of my invention. The term roller as employed herein denotes the entire earth surfacing machine while for the purpose of clarity the term drum as employed herein denotes the cylindrical surface treating elements, e.g., 102,103,105 of FIG. 1. My invention is concerned solely with the positioning of the drums on the roller, therefore, the general makeup and the details of the remainder of the roller are not included herein as such material would add nothing to an understanding of my invention. The drawing purposely exaggerates the skewing of the drums so as to clearly show the departure of my invention from the prior art.

The roller of FIG. 1 comprises: a body 100, a cantilevered drum mounting arbor 106, a rear driven drum 105, a front drum mounting 101 and a skewed pair of drums 102, 103. The drum mounting 101 serves to support the pair of skewed axles and to retain those axles in a common horizontal place. Lines extending from the central ends of the axles (the ends which are closest to each other) ideally meet in said common horizontal plane. In practice the common horizontal plane must be considered to have substantial thickness to fulfill this condition. The angle included by the extended lines is a straight angle (180) minus the sum of the angles of skew of the individual drums from the direction of roller travel. In the practice of my invention each drum, e.g., 102, 103 of the skewed pair may be skewed only a few degrees from the line 110 which is perpendicular to the line 111 which is the line of roller travel. In a typical case each drum may be skewed from 2 to from said line 110. Such typical angle of skew is not to be considered to be limiting since the greater the skew angle the greater the improvement in roller performance. However, since there is a combined scraping and rolling action there is a tendency for a skewed drum to scour the surface being treated. This tendency increases with skew angle and in the case of surface materials, e. g., a bituminous asphalt having a high coefficient of friction the skew angle may if necessary be held to a lower value than in the case of materials, e.g., earth, having a lower coefficient of friction.

As indicated earlier herein, a skew mounted drum causes the roller to have a tendency to travel along a line, e.g., 112 which is perpendicular to the line of the axle of the skewed drum. The tendency to follow such a path is a direction function of the width of the drum. The skew mounted pair of drums 102, 103 of the illustrative embodiment of FIG. 1 are shown to be of equal width and the drums oppositely and equally skewed so as to have opposite but equal tendencies. Accordingly, the skew mounted pair of drums of FIG. 1 permit the roller to be steered by manually positioning the drum mounting 101 about the pivot 104. The positioning of the mounting 101 is accomplished through the use of appropriate power assists, e.g., hydraulic driven pistons. The roller of FIG. 1 may be propelled with the skewed pair of drums 102, 103 advancing ahead of the single drum 105 or vice versa.

Advantageously, drums mounted as shown in the illustrative embodiment of FIG. 1 increase the uniformity of compaction of the material being rolled and provide a more even surface. The improvement in performance can be explained on the basis of my improved roller performing a leveling function similar to the leveling action of a blade carrying machine such as a road grader and the compacting function of a normal roller.

The drums 102, 103 of FIG. 1 are spaced apart and this results in the portion of the surface between these drums being untreated by these drums. This intermediate surface is treated by the drum and by the drums 102, 103 during succeeding passes of the roller. The intermediate surface which is untreated by a single pass of the drums 102, 103 is shown in FIG. 2 which is a front view of the roller of FIG. 1. This untreated surface is labeled 271 in FIG. 2.

FIG. 3 is a side view which shows the arbor 106, the drum mounting 101 and a typical skew mounted drum 103.

FIG. 4 shows in plain view the drum mounting 101 (this corresponds to 101 in FIG. 1) along with mountings 451, 452 for supporting the axle 453 from the mounting 101. In this view the drum 103 is wider than the drum 102. Accordingly, the skew angle of the drum 102 is greater than the skew angle of the drum 101.

FIGS. 5 and 6 show alternative drum mounting arrangements. The drums 502, 503 are unsymmetrically mounted in order to minimize the width of the untreated surface between the skewed drums. Each drum 502, 503 has a recess in the end thereof to permit one drum to move within the space of the other drum without interference. This arrangement mounts on a straight mounting 501 and serves to reduce the width but not eliminate the untreated intermediate surface.

FIG. 6 is another possible mounting arrangement which is angled to accommodate the mounting of a skew mounted pair of drums in a manner which further reduces or eliminates the untreated intermediate surface. The mounting 601 is arranged to carry the drums 602, 603.

Although in each instance the skew mounted drums of a pair have been shown to be of equal width and mounted at equal skew angles such parameters are not essential to the practice of my invention. Drums of unequal width may be utilized as a skew mounted pair so long as their respective skew angles are proportioned to permit steering of the roller. The proper adjustment of skew angle for rollers of different widths must be determined experimentally to accomplish easy steering.

What is claimed is:

1. A multiple drum roller comprising: a body; a pair of surface treating drum means mounted on a corresponding pair of independent axles; drum mounting means operatively connected to said body and adapted to support and to maintain said axles parallel to each other in a common horizontal plane, said axles being skew arranged on said mounting means such that lines extending from the central ends of said axles tend to intersect at a point in said common horizontal plane, said pair of surface trating drum means are of unequal width and said lines extending from said central ends of said axles are, in said common horizontal plane, skewed unequally from the line which defines the direction of roller travel, the line extending from the axle of the drum of smaller width having the greater angle of skew from said line defining the direction of roller travel.

2. A multiple drum roller comprising: a body; a pair of surface treating drum means mounted on a corresponding pair of independent axles; drum mounting means operatively connected to said body and adapted to support and to maintain said axles parallel to each other in a common horizontal plane, said axles being skew arranged on said mounting means such that lines extending from the central ends of said axles tend to intersect at a point in said common horizontal plane, at least one of said surface treating drum means comprises a flanged open end and said drum means are mounted unsymetrically on said mounting means such that the other drum means of said pair invades the open ended cylinder defined by said flanged open end. 

1. A multiple drum roller comprising: a body; a pair of surface treating drum means mounted on a corresponding pair of independent axles; drum mounting means operatively connected to said body and adapted to support and to maintain said axles parallel to each other in a common horizontal plane, said axles being skew arranged on said mounting means such that lines extending from the central ends of said axles tend to intersect at a point in said common horizontal plane, said pair of surface trating drum means are of unequal width and said lines extending from said central ends of said axles are, in said common horizontal plane, skewed unequally from the line which defines the direction of roller travel, the line extending from the axle of the drum of smaller width having the greater angle of skew from said line defining the direction of roller travel.
 2. A multiple drum roller comprising: a body; a pair of surface treating drum means mounted on a corresponding pair of independent axles; drum mounting means operatively connected to said body and adapted to support and to maintain said axles parallel to each other in a common horizontal plane, said axles being skew arranged on said mounting means such that lines extending from the central ends of said axles tend to intersect at a point in said common horizontal plane, at least one of said surface treating drum means comprises a flanged open end and said drum means are mounted unsymetrically on said mounting means such that the other drum means of said pair invades the open ended cylinder defined by said flanged open end. 